I use the section plane on sketchUp to provide an idea of internal spaces to clients, check headroom at key points, detailing internal finishes (windowboards, cornices, etc) and for checking the integrity of the model. It doesn't mean I want to carve the thing up..

Not sure that it would involve transparency though - when the plane is visible, all objects are displayed as though a boolean diff had been carried out, when hidden the boolean is ignored. I imagine that's a simplistic explanation for something fiendishly complicated..

Yes, that's a good interpretation. One creates a transparent plane that will move forward and backward, cutting a structure like a boolean difference but just in a display mode. It may do more than that, I don't really use Sketchup but this can show a section through any portion of, say, a building to take a client through on the fly.
Thanks for considering it.
cheers,
eric

If it helps you can place a plane in your model and generate an intersection curve using the Isect command 'Construct > Curve > Isect' then enable History on the Plane and the intersection curves, in that way when you move the Plane the section will update also.